Four national-level weight-lifters were killed and two others, including a world champion, were seriously injured when the car that they were travelling met with an accident near the Delhi-Haryana border on Sunday, police said.The accident took place at around 4 a.m., near Alipur village of Delhi, close to the Singhu border between Delhi and Haryana.The victims were travelling on the Delhi-Panipat National Highway-1 in a Swift Dezire car. While four weight-lifters were killed in the accident, Saksham Yadav, who won a gold medal in the 2017 weight-lifting championship for the country, was seriously injured along with another weightlifter, a police official said.Yadav and the other injured weight-lifter were rushed to the Max Hospital in New Delhi's Shalimar Bagh for treatment.The car, according to the official, first hit a divider and then crashed into an electricity pole.Due to severe impact, the car's roof was blown away. The official said that the driver was speeding despite dense fog in the area.The weight-lifters were travelling from Panipat towards Delhi.